JP2013156594A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high prevention effect against peeping from the side, to reduce burdens on a CPU, to eliminate the necessity of additional costs, and to enable turning ON/OFF of viewing angle control.SOLUTION: A display device 1 includes a liquid crystal panel 26 having predetermined viewing angle characteristics. The display device 1 performs predetermined gamma curve conversion for original image data by using a conversion table for the predetermined gamma curve conversion according to the viewing angle characteristics of the liquid crystal panel 26. The display device 1 combines a predetermined inclined viewing image according to the viewing field characteristics of the liquid crystal panel 26 with image data after the gamma curve conversion to generate synthetic image data, and displays the synthetic image data on the liquid crystal panel 26.

Description

  The present invention relates to a display device including a liquid crystal display (LCD), a viewing angle control method for a liquid crystal display, a viewing angle control program, and a portable terminal.

  Conventionally, for example, a technique for controlling the viewing angle of the liquid crystal display has been known as a technique for preventing information displayed on a liquid crystal display of a mobile phone terminal from being looked into by others from the side. It has been.

  Conventionally, there are three known methods for controlling the viewing angle of the liquid crystal display, such as the following first viewing angle control method to third viewing angle control method.

  As disclosed in Non-Patent Document 1, the first viewing angle control method includes mounting a viewing angle control liquid crystal display on a liquid crystal display for video display, and controlling the viewing angle. This is a method for controlling the viewing angle.

  The second viewing angle control method is a method for reducing the contrast value of data displayed on the liquid crystal display as disclosed in Non-Patent Document 2.

  As disclosed in Non-Patent Document 3, the third viewing angle control method is a method in which data displayed on the liquid crystal display is data in which front-view image data and oblique-view image data are mixed.

  In addition, as a conventional viewing angle control method, a technique disclosed in Japanese Patent Application Laid-Open No. 2007-17988 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2009-64025 (Patent Document 2) is also known. ing.

  Patent Document 1 discloses a liquid crystal display panel that displays an image by spatial light modulation, a first arrangement in a first mode in which an image displayed using the liquid crystal display panel is visible from a wide viewing angle, and the liquid crystal display. A viewing angle that switches the liquid crystal between the second mode and the second arrangement in which the image displayed using the panel is visible only from a narrow viewing angle, and performs in-plane switching between the public and private modes. A control method is disclosed.

  Further, in Patent Document 2, a liquid crystal display panel that displays an image by spatial light modulation is used as the display panel, and an image displayed using the liquid crystal display panel is in a first mode in which the image can be viewed from a wide viewing angle. A display device is configured by a circuit that performs switching between the first arrangement and the second arrangement in the second mode in which the image displayed using the liquid crystal display panel can be viewed only from a narrow viewing angle in the liquid crystal. A viewing angle control method that achieves in-plane switching of modes is disclosed.

[Search July 1, 2010], Internet <URL: http://www.sharp.co.jp/products/device/about/lcd/veil/index.html> [Search July 1, 2010], Internet <URL: http://www.n-keitai.com/n703id/fc.html> [Search July 1, 2010], Internet <URL: http://www.sharp.co.jp/products/sb831sh/text/veilview.html>

JP 2007-17988 A (FIG. 1) JP 2009-64025 A (FIG. 1)

  However, the first viewing angle control method described above can control the viewing angle only in one direction such as the left-right direction. In addition, since the first viewing angle control method needs to add another liquid crystal display for controlling the viewing angle, the cost increases and the mechanical thickness also increases.

  In the second viewing angle control method described above, since the contrast of the display image is lowered, for example, the image from the front becomes whitish and difficult to see. Further, the second viewing angle control method has a small control effect when viewed from an oblique direction.

  In the third viewing angle control method described above, the process of creating image data to be displayed on the liquid crystal display becomes complicated, and the calculation process becomes enormous as the resolution of the image increases, which places a burden on the CPU and the like. Note that the techniques described in Patent Document 1 and Patent Document 2 are also complicated in image processing, as with the third viewing angle control method, and burden the CPU and the like.

  The present invention has been proposed in view of such circumstances, and has a high prevention effect against side peeping, and has a low burden on the CPU and does not require additional cost. An object is to provide an angle control method, a viewing angle control program, and a portable terminal.

  The display device of the present invention includes a display panel unit having a predetermined viewing angle characteristic, a data holding unit holding predetermined oblique viewing image data corresponding to the predetermined viewing angle characteristic of the display panel unit, and image data conversion And an image composition unit. The image data conversion unit does not change the luminance difference on the low gradation side before and after conversion with respect to the original image data displayed on the display panel, while the luminance difference on the high gradation side is after conversion rather than before conversion. The original image data is converted so that becomes smaller. In addition, the image composition unit generates composite image data in which predetermined image data for oblique viewing is combined with the image data converted by the image data conversion unit. And the display apparatus of this invention displays the synthetic | combination image data by an image synthetic | combination part on a display panel part. Thereby, the display apparatus of this invention solves the subject mentioned above.

  The display device according to the present invention includes a display panel unit having a predetermined viewing angle characteristic, a predetermined conversion table for gamma curve conversion corresponding to the predetermined viewing angle characteristic of the display panel unit, and a predetermined oblique viewing image. A data table holding unit for holding data. Further, the display device of the present invention includes a gamma curve conversion unit that performs a predetermined gamma curve conversion on the original image data displayed on the display panel unit using a conversion table, and a predetermined gamma curve conversion on the image data after the gamma curve conversion. An image composition unit that generates composite image data obtained by combining the oblique viewing image data, and displays the composite image data on the display panel unit. Thereby, the display apparatus of this invention solves the subject mentioned above.

  The viewing angle control method of the present invention is a viewing angle control method for a display device including a display panel unit having a predetermined viewing angle characteristic. In the viewing angle control method of the present invention, the luminance difference on the low gradation side does not substantially change before and after the conversion with respect to the original image data displayed on the display panel unit, while the luminance difference on the high gradation side is the same as that before the conversion. And converting the original image data so that the converted image data becomes smaller, and the image data after the conversion includes predetermined oblique view required image data corresponding to a predetermined viewing angle characteristic of the display panel unit. The method includes a step of generating combined image data in combination, and a step of displaying the combined image data on the display panel unit. Thereby, the viewing angle control method of the present invention solves the above-described problems.

  The viewing angle control method according to the present invention is a viewing angle control method for a display device including a display panel unit having a predetermined viewing angle characteristic. And the viewing angle control method of the present invention performs a predetermined gamma curve conversion on the original image data using a conversion table for a predetermined gamma curve conversion according to the viewing angle characteristics of the display panel unit, A step of generating composite image data by combining the image data after the gamma curve conversion with predetermined oblique viewing image data according to the viewing angle characteristics of the display panel, and a step of displaying the composite image data on the display panel unit And have. Thereby, the viewing angle control method of the present invention solves the above-described problems.

  The viewing angle control program of the present invention is a viewing angle control program for a display device including a display panel unit having a predetermined viewing angle characteristic. The viewing angle control program does not change the luminance difference on the low gradation side before and after conversion with respect to the original image data displayed on the display panel unit, while the luminance difference on the high gradation side is after the conversion than before the conversion. The image data conversion unit that converts the original image data so that the image data becomes smaller, and predetermined oblique view required image data corresponding to the predetermined viewing angle characteristic of the display panel unit is added to the converted image data. The display device is operated as an image composition unit that generates combined image data in combination and a display control unit that displays the composite image data on the display panel unit. Thereby, the viewing angle control program of the present invention solves the above-mentioned problem.

  The viewing angle control program of the present invention is a viewing angle control program for a display device including a display panel unit having a predetermined viewing angle characteristic. The viewing angle control program uses a conversion table for predetermined gamma curve conversion according to the viewing angle characteristics of the display panel unit, and a gamma curve conversion unit that performs predetermined gamma curve conversion on the original image data; An image composition unit that generates composite image data by combining the image data after the gamma curve conversion with predetermined oblique viewing image data according to the viewing angle characteristics of the display panel unit, and the composite image data to the display panel unit A display device is operated as a display control unit to be displayed. Thereby, the viewing angle control program of the present invention solves the above-mentioned problem.

  The portable terminal of the present invention of the present invention includes a display panel unit having a predetermined viewing angle characteristic, a data holding unit holding predetermined oblique viewing image data according to the predetermined viewing angle characteristic of the display panel unit, An image data conversion unit and an image composition unit are provided. The image data conversion unit does not change the luminance difference on the low gradation side before and after conversion with respect to the original image data displayed on the display panel, while the luminance difference on the high gradation side is after conversion rather than before conversion. The original image data is converted so that becomes smaller. In addition, the image composition unit generates composite image data in which predetermined converted image data is combined with the converted image data. And the portable terminal of this invention displays the synthesized image data by an image synthetic | combination part on a display panel part. Thereby, the portable terminal of this invention solves the subject mentioned above.

  The portable terminal of the present invention includes a display panel unit having a predetermined viewing angle characteristic, a conversion table for converting a predetermined gamma curve according to the viewing angle characteristic of the display panel unit, and predetermined image data for oblique viewing. And a data table holding unit for holding. Furthermore, the portable terminal of the present invention includes a gamma curve conversion unit that performs a predetermined gamma curve conversion on the original image data using a conversion table, and a predetermined oblique view image data in the image data after the gamma curve conversion. And an image composition unit that generates composite image data combining the two, and displays the composite image data on the display panel unit. Thereby, the portable terminal of this invention solves the subject mentioned above.

  Here, in the present invention, the predetermined oblique viewing image data is a monochrome image consisting only of data within a predetermined gradation range. For example, when the image data can take from 0 gradation to 255 gradation, The gradation range consists of 0 to 30 gradations.

  Further, in the present invention, when one pixel of the image is composed of the first to third sub-pixels, the image composition unit converts the image data converted by the image data conversion unit and a predetermined oblique viewing image. The combined image data is generated by alternately combining the data for each sub-pixel. Alternatively, the image composition unit generates composite image data by alternately combining the image data converted by the image data conversion unit and predetermined oblique viewing image data for each pixel.

  That is, according to the present invention, predetermined oblique viewing image data in which the gradation range is 0 to 30 gradations is applied to the image data after conversion by the image data conversion unit for each subpixel or 1 The composite image data that is alternately combined for each pixel is displayed. Therefore, according to the present invention, the image viewed from the front is substantially free from image quality deterioration, while the image viewed obliquely is very difficult to see.

  Further, in the present invention, in the oblique view with respect to the display panel unit, the luminance difference on the low gradation side does not substantially change before and after the gamma curve conversion, and the luminance difference on the high gradation side is smaller than that before the gamma curve conversion. It consists of a correspondence table of gradation values and luminance values that become smaller after curve conversion. That is, according to the present invention, the gamma curve conversion corresponding to the viewing angle characteristic of the display panel unit is performed using the conversion table. For this reason, according to the present invention, calculation for gamma curve conversion becomes unnecessary.

  In the present invention, for original image data to be displayed on a display panel unit having a predetermined viewing angle characteristic, the luminance difference on the low gradation side does not substantially change before and after the conversion, whereas the luminance difference on the high gradation side is different from that before the conversion. In addition, the data conversion is performed so that the converted image becomes smaller, and further, the combined image data synthesized by combining the predetermined oblique viewing image data according to the viewing angle characteristics of the display panel is displayed on the display panel unit. Yes. Thereby, in this invention, the high prevention effect with respect to peeping from the side can be acquired, without putting a burden on CPU or requiring additional cost.

  Further, the present invention performs a predetermined gamma curve conversion on the original image data using a conversion table for predetermined gamma curve conversion according to the viewing angle characteristics of the display panel unit, and the image after the gamma curve conversion. Composite image data obtained by combining data with predetermined oblique viewing image data according to the viewing angle characteristics of the display panel is displayed on the display panel unit. Thereby, in this invention, the high prevention effect with respect to peeping from the side can be acquired, without putting a burden on CPU or requiring additional cost.

It is a block diagram which shows schematic structure of the principal part of the display apparatus of this invention embodiment. It is a grab showing a luminance gamma curve in a VA type liquid crystal panel. It is a figure for demonstrating the mode of the transition of the image data by the gamma curve conversion process performed by the display apparatus of this embodiment at the time of a narrow viewing angle mode, and the composition process of the image data for oblique viewing. It is a figure used for description of a front view image and a diagonal view image when the display apparatus of this embodiment is set to the narrow viewing angle mode. It is a figure used for description of a front view image and a diagonal view image when the display apparatus of this embodiment is set to the wide viewing angle mode. It is a graph which shows the gamma curve with which a VA type liquid crystal panel is provided, and the gamma curve after predetermined | prescribed gamma curve conversion calculation. It is a graph used for description of gradation in the narrow viewing angle mode and gradation in the wide viewing angle mode. It is a figure used for description of the normal pixel arrangement | sequence in the liquid crystal panel of a display apparatus. It is a figure used for description of the pixel arrangement corresponding to the image data for oblique viewing of this embodiment. As a first synthesis process example of image data after gamma curve conversion processing and image data for oblique viewing, composite image data when image data after gamma curve conversion processing and image data for oblique viewing are combined for each subpixel It is a figure used for description of the pixel array corresponding to this. As a second synthesis processing example of the image data after the gamma curve conversion processing and the image data for oblique viewing, the combined image data when the image data after the gamma curve conversion processing and the image data for oblique viewing are combined for each pixel. It is a figure used for description of a corresponding pixel arrangement. It is a block diagram which shows the schematic internal structural example of the mobile telephone terminal provided with the display apparatus of this embodiment. It is a flowchart which shows the flow of a process at the time of a control and calculating part performing the viewing angle control application program which the mobile telephone terminal of this embodiment acquired.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Main configuration]
FIG. 1 shows a schematic configuration of a main part of a display device 1 according to an embodiment of the present invention. The display device 1 according to the present embodiment includes various types such as a mobile phone terminal, a PDA (Personal Digital Assistant), a notebook personal computer, a portable game machine, a portable digital television receiver, and a portable navigation terminal. It can be used as a display unit for equipment.

  In FIG. 1, the display device 1 of this embodiment includes a CPU unit 10, a display control unit 11, and a display unit 12 as main components. In addition, although the display apparatus 1 of this embodiment is also provided with the other structure mounted in general apparatuses, such as a power supply unit, an operation unit, an external communication unit, for example, those illustration and description are abbreviate | omitted.

  The CPU 10 unit generates image data displayed on the liquid crystal panel 26 of the display unit 12 and an LCD (Liquid Crystal Display) driver drive control signal of the display unit 12 and outputs the generated image data to the display control unit 12. In addition, the CPU unit 10 generates an LED (Light Emitting Diode) current adjustment signal and outputs it to the LED driver 23 of the display control unit 12.

  The display control unit 12 includes an LCD controller 22 and an LED driver 23. The LCD controller 22 outputs the image data supplied from the CPU unit 10 to the LCD driver 24 of the display unit 12 at the subsequent stage. The LCD controller 22 generates an LCD drive signal based on the LCD driver drive control signal supplied from the CPU unit 10 and outputs the LCD drive signal to the LCD driver 24. The LED driver 23 generates an LED drive current based on the LED current adjustment signal supplied from the CPU unit 10 and outputs the LED drive current to the LED 25 of the display unit 12 at the subsequent stage.

  The display unit 12 includes a liquid crystal panel 26, an LCD driver 24, and an LED 25. The liquid crystal panel 26 is, for example, a so-called VA (Vertical Alignment) type, TN (Twisted Nematic) type, or ECB (Electrically Controlled Birefringence) type LCD panel. The LCD driver 24 supplies the LCD drive signal supplied from the display control unit 11 in the previous stage to the liquid crystal panel 26 and operates each pixel of the liquid crystal panel 26 according to the image data supplied from the display control unit 11. Let Further, the LED 25 emits light by the LED drive current supplied from the LED driver 23 of the display control unit 11. As a result, an image based on the image data is displayed on the liquid crystal panel 26.

  In the display device 1 of the present embodiment, the function of the LCD controller 22 may be performed by the CPU unit 10. In this case, the CPU unit 10 outputs the image data and the LCD drive signal, which are the LCD driver. 24.

[Characteristics of LCD panel]
In the display device 1 of the present embodiment, the liquid crystal panel 26 is any one of the VA type, the TN type, and the ECB type as described above.

  Here, if the liquid crystal panel is of the VA type, the luminance gamma curve in the VA type varies depending on the angle when viewing the liquid crystal panel, that is, the viewing angle, as shown in FIG. 2, the horizontal axis represents the color gradation i, the vertical axis represents the luminance Y, and the luminance Y when the gradation i is “0” (black) when the liquid crystal panel is viewed from the front is “ The luminance Y is “1” when the gradation is “255” (white) when viewed from the front. In FIG. 2, a curve indicated by a solid line in the drawing represents a gamma curve in a front view when the liquid crystal panel is viewed from the front, and a curve indicated by a dotted line in the drawing indicates the liquid crystal panel viewed from an oblique direction. This represents a gamma curve in the case of oblique viewing.

  As shown in FIG. 2, in the VA type liquid crystal panel, when the gamma curve in the oblique view is compared with the gamma curve in the front view, the luminance difference of the oblique gamma curve is the front on the low gradation side. On the other hand, the luminance difference of the oblique gamma curve is smaller than the luminance difference of the gamma curve of the front view. In other words, on the low gradation side, the tangent angle of the oblique gamma curve is larger than the tangential angle of the front view gamma curve. The luminance difference between ix1 is larger in the luminance difference yb in the oblique view than in the front view. On the other hand, on the high gradation side, the angle of the tangent of the oblique gamma curve is smaller than the angle of the tangent of the front view gamma curve, and therefore, between a certain gradation ix2 and gradation ix3 on the high gradation side. The brightness difference is larger in the brightness difference yd in the oblique view than in the front view.

  In the example of FIG. 2, only the VA type is described as an example, but the TN type and the ECB type have the same characteristics.

[Viewing angle control utilizing the viewing angle characteristics of LCD panels]
The display device of the present embodiment makes use of the viewing angle characteristics of the liquid crystal panel as described above, so that the display image on the liquid crystal panel 26 can be viewed without any problem when viewed from the front. When viewing, it is possible to control the viewing angle so that the display image on the liquid crystal panel 26 is substantially invisible.

  That is, in the present embodiment, the viewing angle control is such that the luminance difference on the low gradation side does not substantially change before and after conversion with respect to the original image data displayed on the liquid crystal panel 26, while the luminance difference on the high gradation side is converted. Data conversion is performed so that the converted image data is smaller than before conversion, and predetermined oblique viewing image data corresponding to the viewing angle characteristics of the liquid crystal panel 26 is combined with the converted image data. This is realized by using the subsequent image data as display data on the liquid crystal panel 26. More specifically, in the present embodiment, as shown in FIG. 3, the viewing angle control is performed on the viewing angle characteristics of the liquid crystal panel 26 using the conversion table described later with respect to the original image data OP. In accordance with a predetermined gamma curve conversion process, predetermined image data SP for oblique viewing corresponding to the viewing angle characteristics of the liquid crystal panel is synthesized with the image data CP after the gamma curve conversion process. This is realized by using the image data VP as display data on the liquid crystal panel 26.

  In the present embodiment, the combined image data VP shown in FIG. 3 is displayed on the liquid crystal panel 26, so that the user UA located substantially in front of the liquid crystal panel 26 has the original data as shown in FIG. A display image (front-view image VUA) substantially the same as the image data OP is displayed can be seen. On the other hand, the users UB and UC located obliquely with respect to the liquid crystal panel 26 will see images such as the obliquely viewed images VUB and VUC shown in FIG. VUA is almost invisible.

  The display device 1 according to the present embodiment is not limited to the narrow viewing angle mode in which the viewing angle is narrowed by narrowing the viewing angle as shown in FIGS. By using the original image data OP as the display image data vp of the liquid crystal panel 26 as it is, a wide viewing angle mode in which substantially the same images vua, vub, and vuc are shown to the users UA, UB, and UC is possible. And the display apparatus 1 of this embodiment can be suitably switched between the narrow viewing angle mode and the wide viewing angle mode based on an instruction from the user or by automatic control of the display apparatus 1 itself.

[Details of gamma curve conversion processing in narrow viewing angle mode]
In the present embodiment, the predetermined gamma curve conversion process performed on the original image data OP in the narrow viewing angle mode is performed using a conversion table generated or prepared in advance based on the following calculation. Is called.

  FIG. 6 shows a gamma curve provided in the VA type liquid crystal panel and a gamma curve after the predetermined gamma curve conversion calculation. In FIG. 6, the horizontal axis represents the color gradation i, the vertical axis represents the luminance Y, and the luminance Y when the gradation i is “0” (black) when the liquid crystal panel is viewed from the front is “ The luminance Y is “1” when the gradation is “255” (white) when viewed from the front. In FIG. 6, the curve indicated by the solid line in FIG. 6 represents the gamma curve before the gamma curve conversion calculation in the front view when the liquid crystal panel is viewed from the front as in FIG. 2, and is indicated by the dotted line in the figure. The curve represents the gamma curve before the gamma curve conversion calculation in the case of oblique viewing of the liquid crystal panel as seen from the diagonal as in FIG. In FIG. 6, the curve indicated by the alternate long and short dash line in the figure represents the gamma curve after the gamma curve conversion calculation in the front view when the liquid crystal panel is viewed from the front, and the curve indicated by the alternate long and two short dashes line in the figure is The gamma curve after the gamma curve conversion calculation in the case of oblique viewing when the liquid crystal panel is viewed from an oblique direction is shown.

  Here, the gamma curve conversion calculation is expressed by the following formulas (1) to (4). However, i in the following formula represents the gradation of the color input in the wide viewing angle mode (range 0 to 255), Ycal (i) represents the luminance of the i-th gradation after the conversion calculation, Ydef (i) Represents the actual luminance of the liquid crystal panel of the i-th gradation before the conversion calculation, and CRcal represents a pseudo contrast value to be displayed (in this embodiment, the contrast value is less than 10, for example).

Ycal (i) = A × Ydef (i) + B (1)

A = (Ydef (255) -C) / (Ydef (255) -Ydef (0)) (2)

B = {(C−Ydef (0)) × Ydef (255)} / (Ydef (255) −Ydef (0)) (3)

C = Ydef (255) / CRcal (4)

In the equations (1) to (4), Ycal (i) is obtained from i = 0 to 255 gradations.

  Thereafter, a conversion table of gradation j and gradation i is calculated so as to satisfy the following formula (5). However, in the following formula, j indicates the gradation of the color (in the range of 0 to 255) input in the narrow viewing angle mode, and the gradation j and gradation i have the relationship shown in FIG. In FIG. 7, the horizontal axis represents the gradation i in the wide viewing angle mode, and the horizontal axis represents the gradation j in the narrow viewing angle mode, and these gradations have a range of 0 to 255. .

Ycal (i) ≒ Ydef (j) (5)

Thereafter, in the present embodiment, in the narrow viewing angle mode, the conversion table representing the correspondence between the gradation and the luminance as described above is used, and the gamma with respect to the original image data OP is expressed by the following equation (6). The image data CP after the gamma curve conversion process that has been subjected to the curve conversion process is generated.

j = X (i) (6)

In this embodiment, when the gamma curves before and after the gamma curve conversion process are compared, as shown in FIG. 6, the gamma curve in the front view is the luminance Ydef (i) before the gamma curve conversion process. The luminance Ycal (i) after the gamma curve conversion process is increased. In addition, the gamma curve in the case of oblique viewing does not change much before and after the gamma curve conversion process on the low gradation side, whereas on the high gradation side, the gamma curve with respect to the brightness difference before the gamma curve conversion process. The luminance difference after the conversion process is made small. That is, as in FIG. 2 described above, the luminance difference between the low gradation side gradation ix0 and gradation ix1 and the luminance difference between the high gradation side gradation ix2 and gradation ix3 are taken as examples. In this case, the luminance difference yb before the gamma curve conversion process and the luminance difference yb ′ after the gamma curve conversion process have not changed much on the low gradation side, but on the high gradation side, the luminance difference yb ′ before the gamma curve conversion process has not changed so much. The luminance difference yd ′ after the gamma curve conversion process is smaller than the luminance difference yd.

  Thus, according to the display device 1 of the present embodiment, in the narrow viewing angle mode, as shown in FIG. 4, the front view image VUA is easy to see, while the oblique view images VUB and VUC have a luminance difference. It becomes a little difficult to see. Further, according to the display device 1 of the present embodiment, in the narrow viewing angle mode, the luminance of the front view gamma curve is higher after the conversion process than before the gamma curve conversion process, Since the luminance difference before and after the gamma curve conversion process is hardly changed on the low gradation side with respect to the gamma curve, when the oblique image data SP is synthesized, the image itself becomes dark and the front view image is changed. It prevents it from becoming difficult to see.

[Image data for oblique viewing in narrow viewing angle mode]
In the present embodiment, in the narrow viewing angle mode, the predetermined oblique viewing image data SP combined with the image data CP after the gamma curve conversion processing is preliminarily stored as image data as follows, for example. Have it ready. In the following description, it is assumed that the gradation of the image data can take from 0 to 255 gradations.

  The oblique viewing image data SP of the present embodiment is, for example, an image having 0 to 30 gradations. Note that the 30 gradations are only examples, and other gradations may be used, and it is desirable to use optimal values as appropriate depending on the liquid crystal panel to be used. Of the 0 to 30 gradations, only the 0 gradation and the 30 gradation are used as the oblique viewing image data. In this way, by using only the 0th gradation and the 30th gradation, the oblique viewing image data SP can be seen more when the liquid crystal panel 26 is viewed obliquely in the narrow viewing angle mode. Can be difficult.

  The oblique viewing image data SP of the present embodiment is a monochrome image. Thus, by using a monochrome image as the oblique view image data SP, it is possible to prevent the display image in front view from being deteriorated by the oblique view image data SP and becoming difficult to see.

  Furthermore, the oblique view image data SP of the present embodiment may be any image data such as a geometric pattern, a character, and a photograph, and is not limited.

[Composition processing of image data after gamma curve conversion processing and image data for oblique viewing]
In the narrow viewing angle mode, the display device 1 according to the present embodiment combines the image data CP after the gamma curve conversion process and the image data SP for oblique viewing, and the combined image data VP is The display data is displayed on the liquid crystal panel 26.

  Hereinafter, the image data composition processing will be described with reference to FIGS.

  8 to 11 each show a pixel arrangement in a liquid crystal panel of a display device.

  FIG. 8 shows a normal pixel arrangement in the liquid crystal panel. That is, as shown in FIG. 8, one pixel of the liquid crystal panel is composed of first to third sub-pixels corresponding to three colors of R (red), G (green), and B (blue). Yes. In the present embodiment, it is assumed that the color of the first subpixel is R, the color of the second subpixel is G, and the color of the third subpixel is B.

  Here, in the following description, the first to third sub-pixels of the pixel in the n-th row and m-th column (n and m are natural numbers of 1 or more) of the pixel array are respectively (n, m, color). It is assumed that That is, in the present embodiment, for example, the first sub-pixel of the pixel in the first row and the first column is represented as (1, 1, R), and the G sub-pixel of the pixel in the first row and the first column is (1, 1, G). The B subpixel of the pixel in the first row and the first column is represented as (1, 1, B). Similarly, for example, the R subpixel of the pixel in the second row and the third column is (2, 3, R), the G subpixel of the pixel in the second row and the third column is (2, 3, G), 2 The B subpixel of the pixel in the third column of the row is represented as (2, 3, B). The pixels and subpixels in other rows and columns are also expressed in the same manner.

  In the present embodiment, the first to third subpixels constituting one pixel have the same gradation in the pixels of the oblique viewing image data SP that is a monochrome image. The first to third sub-pixels constituting one pixel of the oblique viewing image data SP are arranged corresponding to the three R, G, and B sub-pixels. When the monochrome gradation in the first to third sub-pixels of the oblique viewing image data SP is represented by “K”, for example, the first to third three pixels of the n-th row and m-th column are used. The subpixels are represented as (1, 1, K), respectively. In the present embodiment, the oblique image data SP is, for example, data composed of 0 gradation and 30 gradation as described above. Therefore, when the 0 gradation is represented by K = “0k” and the 30 gradation is represented by K = “30k”, for example, the first to third three pixels of the pixel in the n-th row and the m-th column. The subpixels are represented as (1, 1, 0k) or (1, 1, 30k), respectively.

  Further, in the present embodiment, the oblique viewing image data SP has, for example, the 0 gradation and the 30 gradations for each macro pixel of q × q pixels (q is a natural number of 1 or more) consisting of q rows and q columns. They are arranged alternately. FIG. 9 shows an example in which the 0 gradation and the 30 gradation are alternately arranged for each macro pixel composed of 2 × 2 = 4 pixels for two rows and two columns. That is, in the case of the example in FIG. 9, the macro pixels composed of the four pixels in the first row, the first column, the first row, the second column, the second row, the first column, and the second row, the second column are the first to second in each pixel. Each of the three sub-pixels has 0 gradation (“0k”), and the macro pixel consisting of four pixels in the first row, the third column, the first row, the fourth column, the second row, the third column, and the second row, the fourth column is Each of the first to third sub-pixels has 30 gradations (“30k”), and similarly, the third row, the first column, the third row, the second column, the fourth row, the first column, and the fourth row, the second column. The macro pixel consisting of the four pixels of the first, the first to third sub-pixels are 0 gradation ("0k"), the third row third column and the third row fourth column, fourth row third column, The macro pixel consisting of 4 pixels in the 4th row and 4th column has 30 gradations (“30k”) for the first to third sub-pixels, respectively. Has been made. The pixels and subpixels in other rows and columns are also expressed in the same manner.

  FIG. 10 shows, as a first synthesis example of the image data CP after the gamma curve conversion processing and the image data SP for oblique viewing, the image data CP after the gamma curve conversion processing and the oblique viewing for each subpixel. Each pixel when the image data VP after the synthesis processing is generated by alternately combining the image data SP for use is shown.

  In other words, in the first synthesis processing example shown in FIG. 10, n and m are both odd numbers, or n and m are both even numbers.

VP (n, m, R) = CP (n, m, R)
VP (n, m, G) = SP (n, m, K)
VP (n, m, B) = CP (n, m, B)

For pixels where n is odd and m is even, or n is even and m is odd,

VP (n, m, R) = SP (n, m, K)
VP (n, m, G) = CP (n, m, G)
VP (n, m, B) = SP (n, m, K)

It is made.

  Thereby, as shown in FIG. 10, the image data VP after the synthesis process has the above-mentioned four pixels in the first row, the first column, the first row, the second column, the second row, the first column, and the second row, the second column. The 0-gradation (“0k”) data of the image data CP after the gamma curve conversion process and the oblique viewing image data SP are alternately arranged for each sub-pixel. Further, for the four pixels in the first row, the third column, the first row, the fourth column, the second row, the third column, and the second row, the fourth column, the image data CP after the gamma curve conversion processing and the image data SP for oblique viewing are used. Thus, data of 30 gradations (“30k”) are alternately arranged for each sub-pixel. Similarly, for the 4th pixel in the 3rd row, 1st column, 3rd row, 2nd column, 4th row, 1st column, 4th row, 2nd column, the image data CP after the gamma curve conversion processing and the image for oblique viewing are used. Data SP 30 grayscale (“30k”) data are alternately arranged for each sub-pixel, the third row, third column, third row, fourth column, fourth row, third column, fourth row, fourth column. For the four pixels of the eye, the 0-gradation (“0k”) data of the image data CP after the gamma curve conversion processing and the oblique viewing image data SP are alternately arranged for each sub-pixel. The other rows and columns of pixels and subpixels are similarly arranged.

  In the first synthesis process example, n and m are both odd numbers, or n and m are both even numbers.

VP (n, m, R) = SP (n, m, K)
VP (n, m, G) = CP (n, m, G)
VP (n, m, B) = SP (n, m, K)

And n is an odd number and m is an even number, or n is an even number and m is an odd number,

VP (n, m, R) = CP (n, m, R)
VP (n, m, G) = SP (n, m, K)
VP (n, m, B) = CP (n, m, B)

It is good.

  FIG. 11 shows, as a second synthesis example of the image data CP after the gamma curve conversion processing and the image data SP for oblique viewing, the image data CP after the gamma curve conversion processing and for oblique viewing for each pixel. Each pixel when the image data VP after the synthesis process is generated by alternately combining the image data SP is shown.

  That is, in the second synthesis example shown in FIG. 11, for pixels where n and m are both odd numbers or n and m are both even numbers,

VP (n, m, R) = CP (n, m, R)
VP (n, m, G) = CP (n, m, G)
VP (n, m, B) = CP (n, m, B)

For pixels where n is odd and m is even, or n is even and m is odd,

VP (n, m, R) = SP (n, m, K)
VP (n, m, G) = CP (n, m, K)
VP (n, m, B) = SP (n, m, K)

It is made.

  As a result, the image data VP after the composition processing is as shown in FIG. 11 with respect to four pixels in the first row, the first column, the first row, the second column, the second row, the first column, and the second row, the second column. The image data CP after the gamma curve conversion processing is arranged in 2 pixels in the 1st row and the 2nd row and the 2nd row, and the image data SP for oblique viewing is placed in 2 pixels in the 1st row, the 2nd row and the 2nd row, 1st column 0 gradation ("0k") is arranged. In addition, for the 4 pixels in the first row, the third column, the first row, the fourth column, the second row, the third column, and the second row, the fourth column, the two pixels in the first row, the third column, and the second row, the fourth column, The image data CP after the gamma curve conversion process is arranged, and 30 gradations (“30k”) of the oblique viewing image data SP are arranged in two pixels in the first row, the fourth column, and the second row, the third column. Similarly, for the 4 pixels in the 3rd row, 1st column and 3rd row, 2nd column, 4th row, 1st column, 4th row, 2nd column, 2 pixels in 3rd row, 1st column and 4th row, 2nd column The image data CP after the gamma curve conversion processing is arranged, and 30 gradations (“30k”) of the oblique viewing image data SP are arranged in 2 pixels of the fourth row, first column and the third row, second column. The The 4th pixel in the 3rd row, the 3rd column, the 3rd row, the 4th column, the 4th row, the 3rd column, and the 4th row, the 4th column are the 2nd row in the 3rd row, the 3rd row, and the 4th row, the 4th row. The image data CP after the gamma curve conversion process is arranged in the pixel, and the 0th gradation (“0k”) of the image data SP for oblique viewing is displayed in two pixels in the third row, the fourth column, and the fourth row, the third column. Arranged. The other rows and columns of pixels and subpixels are similarly arranged.

  In the second synthesis example, n and m are both odd numbers, or n and m are both even numbers.

VP (n, m, R) = SP (n, m, K)
VP (n, m, G) = CP (n, m, K)
VP (n, m, B) = SP (n, m, K)

For pixels where n is odd and m is even, or n is even and m is odd,

VP (n, m, R) = CP (n, m, R)
VP (n, m, G) = CP (n, m, G)
VP (n, m, B) = CP (n, m, B)

It is good.

[Schematic configuration of mobile phone terminal]
FIG. 12 shows a schematic internal configuration example of a mobile phone terminal provided with the display device of the present embodiment.

  In FIG. 12, a communication antenna 51 is, for example, a built-in antenna, and performs transmission and reception of signal waves for communication with the Internet and the like through a mobile phone network, transmission and reception of telephone calls and emails. The antenna circuit 52 includes an antenna switch, a matching circuit, a filter circuit, and the like, and the transmission / reception circuit unit 53 performs frequency conversion, modulation, demodulation, and the like of transmission / reception signals. The mobile phone terminal of this embodiment can acquire various data and application programs through communication by the communication antenna 51 and the transmission / reception circuit unit 52.

  The audio input / output unit 63 includes a speaker and its peripheral circuit, and a microphone and its peripheral circuit. The speaker and its peripheral circuit are a speaker for reception provided in a mobile phone terminal, a speaker for ringer (ringing tone), an alarm sound, various voice messages, etc. and its peripheral circuit. The supplied audio signal is converted into an acoustic wave and output into the air. The microphone and its peripheral circuit are a microphone for transmitting and collecting external sound and its peripheral circuit, convert an acoustic wave into a sound signal, and send the sound signal to the control / calculation unit 54. The peripheral circuit includes a speaker amplification circuit, a microphone amplification circuit, a decompression decoding circuit for decompressing and decoding the compression-encoded audio data supplied from the control / arithmetic unit 54, and a digital signal after the decompression decoding. Digital / analog conversion circuit for converting audio data into an analog audio signal, analog / digital conversion circuit for converting an analog audio signal input from a microphone into digital audio data, a compression encoding circuit for compressing and encoding the digital audio data, etc. Consists of.

  The display unit 62 corresponds to the display unit 12 shown in FIG. 1 and includes the liquid crystal panel 26, the LCD driver 24, the LED 25, and the like.

  The display control / drive unit 61 corresponds to the display control unit 11 shown in FIG. 1 and includes the LCD controller 22, the LED driver 23, and the like.

  The operation unit 65 includes keys such as a numeric keypad, an utterance key, and an end / power key provided on a casing (not shown) of the mobile phone terminal according to the present embodiment, and operation elements such as a cross key and a jog dial. An operation signal generator that generates an operation signal when the operation element is operated. In the case of the mobile phone terminal of the present embodiment, the operation unit 65 includes a touch panel. The touch panel is, for example, a transparent touch panel, and is disposed on the screen of the liquid crystal panel 26 of the display unit 62.

  The external input / output terminal unit 64 includes, for example, a cable connection connector and an external data communication interface circuit when performing data communication through a cable, a charging terminal and its charging interface circuit when charging an internal battery through a power cable, etc. Consists of. Thereby, the mobile phone terminal of the present embodiment can fetch various data and application programs through the external input / output terminal unit 64.

  The external memory I / F unit 57 includes an external memory slot to which an external memory is attached and detached, an external memory data communication interface circuit, and the like. Thereby, the mobile phone terminal according to the present embodiment can fetch various data and application programs through the external memory.

  The digital broadcast receiving module 56 includes a receiving antenna and a tuner for so-called digital television broadcasting and digital radio broadcasting. The digital broadcast data received by the digital broadcast receiving module 56 can be stored (that is, recorded) in the memory unit 55 after being compressed by the control / arithmetic unit 54, for example. The mobile phone terminal of the present embodiment can also acquire various data and application programs provided through display broadcasting through the digital broadcast receiving module 56.

  The memory unit 55 includes a built-in memory provided in the terminal and a removable card-like memory for storing so-called SIM (Subscriber Identity Module) information. The built-in memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM stores an OS (Operating System), a control program for the control / calculation unit 54 to control each unit, device information of the terminal itself, various initial setting values, dictionary data, various sound data, various application programs, and the like. Storing. This ROM includes a rewritable ROM such as NAND-type flash memory (NAND-type flash memory) or EEPROM (Electrically Erasable Programmable Read-Only Memory), e-mail data, telephone book and mail address book data, static Data of image and moving image content, and other various user setting values can be stored. The various data and application programs stored in the memory unit 55 include not only data prepared in advance but also data and application programs acquired through the communication, external memory, external input / output terminals, and the like. . The RAM stores data as needed as a work area and a buffer area when the control / arithmetic unit 54 performs various data processing.

  Although not shown, the portable information terminal 1 according to the present embodiment includes a short-range wireless communication module such as a wireless LAN or Bluetooth (registered trademark), or a camera unit M for capturing a still image or a moving image. For example, so-called RFID (Radio Frequency-Identification), a non-contact communication module for non-contact communication used in a non-contact type IC card, GPS (Global Positioning) for detecting the current position and movement of the terminal itself System) modules, various sensors for detecting acceleration, direction, temperature, humidity, etc., timepieces that measure time and time, batteries that supply power to each part, and power management ICs that control the power Of course, each component provided in the portable information terminal is also provided.

  The control / arithmetic unit 54 corresponds to the CPU unit 10 shown in FIG. 1, and includes the transmission / reception circuit unit 53, display control / drive unit 61, audio input / output unit 63, external input / output terminal unit 64, digital broadcast receiving module. 56, an external memory I / F unit 57, a GPS module, a non-contact communication module, a short-range wireless communication module, a camera unit, various sensors, an operation unit 65, and the like, and controls various operations as necessary. . The control / arithmetic unit 54 executes a control program and various application programs stored in the memory unit 55.

[Operation flow when obtaining application program for viewing angle control]
In this embodiment, the viewing angle control application program for realizing the viewing angle control as described above may be prepared when the mobile phone terminal is shipped from the factory. For example, the communication, external memory, external input / output It is also possible to obtain it separately via a terminal or the like.

  FIG. 13 shows a flow of processing when the mobile phone terminal of the present embodiment acquires the viewing angle control application program and the control / calculation unit 54 executes the viewing angle control application program. Note that the viewing angle control application program in this case may be activated in response to an instruction from the user, or may be automatically activated when the power is turned on.

  In the flowchart shown in FIG. 13, when the viewing angle control application program is activated, the control / calculation unit 54 first determines whether or not the initial setting for viewing angle control has already been completed as processing in step S1. Here, the initial setting for the viewing angle control is, for example, a display type setting indicating whether the liquid crystal panel mounted on the mobile phone terminal of the present embodiment is the VA, TN, or ECB type. Use setting of the conversion table capable of executing gamma conversion processing optimal for the viewing angle control with respect to the viewing angle characteristics of the liquid crystal panel, and the viewing angle control with respect to the viewing angle characteristics of the liquid crystal panel. The use setting of the image data for oblique viewing that is most suitable for the above can be mentioned. That is, the viewing angle characteristics of the liquid crystal panel differ for each type of VA, TN, and ECB, and also differ for each manufacturer, production lot, and model of the liquid crystal panel. Therefore, it is desirable to use the optimum conversion table for gamma conversion processing and image data for oblique viewing for controlling the viewing angle for each viewing angle characteristic of the liquid crystal panel. For this reason, in the present embodiment, when executing the viewing angle control application program, the type of the liquid crystal panel mounted on the mobile phone terminal and the viewing angle characteristics are optimized for the viewing angle control. Initial setting is performed so as to use a conversion table for gamma conversion processing and image data for oblique viewing. In the determination process of step S1, when it is determined that the initial setting for the viewing angle control has not yet been made, for example, by looking at the initial setting flag or the like, the control / calculation unit 54 advances the process to step S2. . Note that the initial setting of the viewing angle control has not yet been made, for example, when the user separately acquires the viewing angle control application program and installs it on the mobile phone terminal of the present embodiment, and then launches the program for the first time. Can be mentioned.

  In step S2, the control / calculation unit 54 determines the model name, display type, and the like of the terminal itself based on the device information stored in the memory unit 55. If the device information does not include information such as the model name or display type of the own terminal, the control / calculation unit 54 may be, for example, a mobile phone service center to which the own terminal is subscribed through the transmission / reception circuit unit 53. It may be determined by connecting to the mobile phone service center or the like and inquiring the model name or display type of the terminal itself. After the model name and display type determination processing, the control / calculation unit 54 advances the processing to step S3.

  When the processing proceeds to step S3, the control / calculation unit 54 determines the image data for oblique viewing that is optimal for the model name and display type of the terminal, that is, the viewing angle characteristics of the liquid crystal panel mounted on the terminal. The image data for oblique viewing optimal for the viewing angle control is acquired. At the same time, the control / arithmetic unit 54 determines the conversion table for the gamma curve conversion process optimal for the model name and display type of the own terminal, that is, the viewing angle characteristics of the liquid crystal panel mounted on the terminal as the process of step S4. On the other hand, a conversion table optimum for the viewing angle control is acquired. The control / calculation unit 54 at this time, for example, is connected to a mobile phone service center to which the own terminal is subscribed, and the mobile phone service center etc. Visual image data and a conversion table are acquired. That is, in the case of this example, the mobile phone service center has image data for oblique viewing and a conversion table that are optimal for viewing angle control for each model and each display type, and these are obtained from the mobile phone terminal. When a request is made, image data for oblique viewing and a conversion table that are optimal for the model name and display type of the terminal are provided to the mobile phone terminal. Note that the optimal oblique viewing image data and conversion table for each model and display type may be prepared in advance in the viewing angle control application program. In this case, the control / calculation unit 54 performs oblique viewing that is optimal for viewing angle control in the model name and display type of the terminal, from among a plurality of oblique viewing image data and conversion tables prepared in the program. Image data and conversion table are selected.

  When the acquisition of the oblique viewing image data and the conversion table optimal for the model name and display type of the terminal is completed, the control / calculation unit 54 performs the obtained oblique viewing image data and the conversion table as a process of step S5. Are stored in the nonvolatile storage area of the memory unit 55. Then, the control / calculation unit 54 sets an initial set flag indicating that the initial setting for viewing angle control is completed, and then returns the process to step S1.

  If it is determined in step S1 that the initial setting flag is set and the initial setting for the viewing angle control is completed, the control / calculation unit 54 advances the process to step S10.

  When the processing proceeds to step S10, the control / calculation unit 54 determines whether the current viewing angle control mode is the narrow viewing angle mode or the wide viewing angle mode described above. As described above, these viewing angle control modes can be appropriately switched based on an instruction from the user or under the control of the control / calculation unit 54 itself.

  If it is determined in step S10 that the wide viewing angle mode is set, the control / calculation unit 54 proceeds to step S14, and the original image data OP is directly used for the liquid crystal panel 26 as shown in FIG. Display image data vp allows the users UA, UB, UC to display in the wide viewing angle mode in which substantially the same images vua, vub, vuc are shown. After the process of step S14, the control / calculation unit 54 returns the process to step S10.

  On the other hand, if it is determined in step S10 that the mode is the narrow viewing angle mode, the control / calculation unit 54 advances the processing to step S11.

  When the processing proceeds to step S11, the control / calculation unit 54 performs gamma curve conversion on the original image data OP using the conversion table for the gamma curve conversion processing as shown in FIG. Apply processing.

  The control / calculation unit 54 combines the image data SP for oblique viewing in combination with the image data CP after the gamma curve conversion process as the process of step S12.

  Thereafter, the control / arithmetic unit 54 uses the combined image data VP as display data on the liquid crystal panel 26 as the process of step S13. As a result, an image is displayed on the display screen in the narrow viewing angle mode. After the process of step S13, the control / calculation unit 54 returns the process to step S10.

[Summary]
As described above, according to the embodiment of the present invention, it is possible to obtain a high prevention effect against peeping from the side in the narrow viewing angle mode. In the present embodiment, the display image in the narrow viewing angle mode is a combination of image data after gamma curve conversion processing referring to a conversion table prepared in advance and image data for oblique viewing prepared in advance. It is made with an image. In other words, according to the present embodiment, calculation is not required when combining the gamma curve conversion process and the image data, so the burden on the CPU is small, and it is necessary to use a new calculation configuration or a high-performance CPU. There is almost no additional cost. In addition, according to the present embodiment, since the viewing angle control is performed in consideration of the viewing angle characteristics of the liquid crystal panel, it is possible to obtain a high anti-peeping effect for oblique viewing while in the narrow viewing angle mode. The image quality of the front view image hardly deteriorates, and a front view image that is very easy to see can be obtained. Furthermore, according to this embodiment, the narrow viewing angle mode and the wide viewing angle mode can be switched as appropriate.

  The above description of the embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiments, and various modifications can be made according to the design and the like as long as they do not depart from the technical idea according to the present invention.

  The display device of the present invention can be applied to, for example, a PDA (Personal Digital Assistant), a small notebook personal computer, a portable game machine, a portable digital television receiver, a portable navigation terminal, etc., in addition to a cellular phone terminal. .

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 10 ... CPU part, 11 ... Display control part, 12 ... Display part, 22 ... LCD controller, 23 ... LED driver, 24 ... LCD driver, 25 ... LED, 26 ... Liquid crystal panel 51 ... Communication antenna, 52 ... Antenna circuit, 53 ... Transmission / reception circuit section, 54 ... Control / calculation section, 55 ... Memory section, 56 ... Digital broadcast receiving module, 57 ... External memory I / F section, 61 ... Display control / drive section, 62 ... Display section 63 ... Audio input / output unit, 64 ... External input / output terminal unit, 65 ... Operation unit OP ... Original image data, CP ... Image data after gamma curve conversion processing, SP ... Image data for oblique viewing, VP ... After synthesis Image data, UA ... user in front view, UB, UC ... user in oblique view, VUA ... user in front view in narrow viewing angle mode Front view image, VUB, VUC ... Oblique view image viewed by oblique view user in narrow view angle mode, vua ... Front view image seen by front view user in wide view angle mode, vub, vuc ... Wide view angle mode Oblique view image seen by oblique view users

Claims (1)

A display panel unit having a predetermined viewing angle characteristic;
For the original image data displayed on the display panel unit, the luminance difference on the low gradation side does not substantially change before and after conversion, while the luminance difference on the high gradation side is smaller after conversion than before conversion. An image data converter for converting the original image data;
A data holding unit that holds predetermined oblique viewing image data according to a predetermined viewing angle characteristic of the display panel unit;
An image composition unit that generates composite image data in which the predetermined oblique viewing image data is combined with the image data converted by the image data conversion unit;
A display device that displays combined image data from the image combining unit on the display panel unit.